Physical and Applicative Overview Joey Goodknight Physics 129 October 21, 2010

Getting and Getting Rid of Them

 Basic Physical Mechanisms  Antimatter is Everywhere  Too Many Electrons!

How and Why the Positron?

 1 gram of anti-p+ 2 X Joules 4 “Little Boy”s (Hiroshima) 2 “Fat Man”s (Nagasaki) $25,000,000, (2009 Nasa Study)  ~GDP of Yemen  Admittedly only 1/20 of US defense Spending  ~Yearly Nuclear Weapons Spending (1998 )  Containment Unrealistic past atoms  From Space: Classic “Doomsday Theory” Tungaska Event

Sorry, Back to e+/e-…

 EM Phenomenon  3 main methods: γ  e + + e - γ + γ  e + + e - Decay  Other Possibilities?

EE Conservation E=h υ = ~ m e c 2 λ ~1 femtometer υ ~10 23 Hz Well past gamma rays PP Conservation Restricts Diagrams LLeast Expected Femtosecond 800nm focus

 matter+anti-matter  “Nothing”  Much simpler than Prod.  P Conservation  Positronium Bound state L=0, annihilation!

 Dirac 1929  Carl Anderson 1932 under Millikan  Cloud Chamber Tracks  γ  208 Tl 1936 Nobel

They’re All Around Us!

+q -q’ +q’ Goop, full of dipoles

+q -q E=?

 Vacuum Photons Create Virtual Pairs Shield Charge Vacuum  Dielectric  QED Triumph spin  1997 Confirmation

Seein’ inside you

 Weak Force Decay  11 C, 40 K, 13 N, 18 F etc.

e+e- γ γ Photons Come out at 180 degrees to each other Complex Processing Density Map of Tracer

Always a Friend of Solid State Physicists

e+ γ γ Positron Source Na, usually γ Scan Material Correlate emission with annihilation Generate map of open volume defects Gets trapped Live longer Defects are what make many semiconductors cool